Dr. Adashi: It now appears in retrospect that the story begins long before 1981 when a predecessor of the HIV type I virus crossed the species barrier from a chimpanzee to a human.
Dr. Fauci: Right.
Dr. Adashi: How often does a disease make itself known that way? How often do we acquire new diseases through such transspecies migration?
Dr. Fauci: Well, much to the surprise of most people, quite frequently. Let me explain. We get emerging and re-emerging diseases and new diseases all the time. I mean, literally, when I testify before the Congress I'm always telling them each year about a new disease here or there. About 70% of the newly emerging infections are zoonotic in the fact that they jump from an animal species to a human. The issue is that not all of them have a major public health impact. [One example of a disease that does that] frequently is influenza. Typical examples include bird flu, swine flu, etc., but most of the things that jump species are curiosities that affect a relatively small number of people. They give us pause to think but don't have a major impact on global health.
Every once in a while one of these emerging microbes not only jumps species but it explodes through the population the way HIV/AIDS did. . .
